BAGHDAD (AP) -- A car bomb explosion tore through a crowd of Shiite pilgrims returning home Thursday from a religious commemoration, killing at least 20 and reinforcing fears of renewed sectarian violence, according to Iraqi officials.

The blast erupted late in the afternoon in the town of Musayyib, about 60 kilometers (40 miles) south of the Iraqi capital. It targeted worshippers returning from the Shiite holy city of Karbala following the climax of the religious commemoration known as Arbaeen.